I don't think it can work unilaterally, it has to be bilateral and multilateral --eventually having universally open borders --but given the displeasure with the soft equivalent, global economics "globalization", I don't see this happening any sooner.
If "globalization" --which in theory would eventually bring equilibrium to economic effects-- has such resistance and suffers from criticism from the left and right, wile being a "soft" form of migration, imagine how people would receive "hard' worldwide migration. I don't see it being received well, if done unilaterally.